Treaty of Pereyaslav though of all of Ukraine as rightfully belonging under the Tsardom's rule; and by Ukrainians, who fought for a country of their own.b.Because of the (completed by the first half of the 18th century) Polonization of Ruthenian aristocracy, the Ukrainian people became depraved of their national elites. The noble clans saw their position initially as being allied with the Polish state, but in time assumed its fundamental membership attributes. Ukrainian intellectual elites were restored only during the later part of the 19th century.c.Before the Khmelnytsky Uprising, the sejmiks of the Kiev Voivodeship and Bratslav Voivodeship deliberated in the majority Ruthenian language, despite the increasing proportion of the Polish and Lithuanian szlachta settled there. Among the one hundred researched Ruthenian noble families from the region, most were opposed to the Union of Brest and almost all fought under Bohdan Khmelnytsky's command.d.The extreme deterioration of the condition of the Polish and Ruthenian serfs caused the degeneration of their status into a form of slavery, referred to in Polish historiography as wtórna pańszczyzna or wtórne poddaństwo'' [secondary serfdom]. Peasants were basically free people, capable of upward mobility, until the 15th century. After the early modern precipitous decline, significant improvements in the lives of this large majority of the country's population took place only in the middle and later 19th century, in partitioned Poland. References Further reading . . Political history of Lithuania Political history of Poland